The present invention relates to electronic devices, especially changing the color of the cover of an electronic device.
The cover of an electronic device, e.g. a mobile station, has multiple functions like protecting the product from dirt, mechanic stress and electromagnetic interference. The cover can also be used to give a desired appearance to the mobile station. Plastics and metals have certain basic colors, and when producing covers in other colors, these materials can be colored e.g. with paint or lack, coated with a material with the desired color (e.g. chromed) or a plastic cover can be mixed with color pigments. An effect known from prior art is implemented in the Nokia 6110 mobile station. The spectrum of the light reflected by the phone depends on the angle of reflection, and thus it looks as of somewhat different color when viewed from different directions.
Another special effect known from prior art concerning the color of a mobile station is presented in a patent application publication WO 98/56221. The publication presents a cover of a mobile station, which cover changes color reversibly, and the color of which depends on the intensity of the ultra-violet radiation it is subjected to. The capability has been implemented by coating the cover with or by mixing into it crystals that change color when subjected to ultra-violet radiation.
Generally a mobile station comprises a display, and because of this it is quite easy to dial even lengthy phone numbers. However, sometimes the dialing user might forget, which button was last pressed. This can of course be easily found out e.g. by moving one""s eyes from the keyboard to the display, but it would be referable to show, especially to elderly users, the last pressed key or keys, and even more preferably show the order in which they have been pressed.
It would be preferable for a person with children in the family to easily find out from his/her mobile station, if the children of the family have used the phone without permission, or if a call initiated from the mobile station has otherwise been left unfinished.
Manufacturing a mobile station requires relatively high technical know-how, but on the other hand manufacturing e.g. its colored covers and batteries is much simpler and thus more vulnerable to piratism. The original manufacturer should preferably also supply the accessories used in their mobile stations, because a badly fitting colored cover can impair the quality of a well-made mobile station. Unsuitable batteries may also in the worst case cause a security risk. New hard to imitate technical methods should be employed in order to easily distinguish the manufactured product from imitation products.
The present invention is an electronic device, a cover of the electronic device and a method of manufacturing the cover of an electronic device, the outer surface of which cover comprises a material that changes color with temperature, such as the TLC""s or Thermochromic Liquid Crystals manufactured by Hallcrest Ltd. The color of an electronic device manufactured in this way will change with the changes in the temperature of the cover of the electronic device. Heat coming both from inside and outside the unit causes this: kind of changes in temperature.
According to another embodiment of the present invention at least a part of the keys of the electronic device, and/or a key frame surrounding them comprises a material that changes its color reversibly with temperature, in order to show the numbers or operations last selected. When the user has pressed a key and the part of the keyframe surrounding the key on the keyboard that is of room temperature with her finger that is several degrees centigrade warmer than the keyboard, a color-changing area like this first changes its color and then starts slowly to reassume the color of its surroundings. During the reversing period the user can, however, see the key that has a color different from its surroundings, and therefore deduce that the key has been recently used.
An electronic device""s cover according to a third embodiment of the present invention comprises a substance that changes its color in high or low temperature, which color change indicates a temperature hazardously high or low for the mobile station. Preferably the change of color is arranged to take place a little before the temperature of the electronic device reaches a value hazardous to it.
An advantage of the invention is that the use of an electronic device based on a change in temperature can be visibly indicated with a completely passive structure without shortening the standby time of the battery of an electronic device and without any electronic components. As an additional advantage of the present invention the color change can indicate unauthorized and unwitting use of the electronic device. When a device according to the present invention has been used without authorization, it returns to a certain balance temperature and its color will correspond to this temperature and the cover temperature profile, but during the reversing it can easily be seen that the device has been used, with the prerequisite that, e.g. a mobile station heats up to a temperature different from its normal environment, when pressed against the ear, and enters the color change region of a temperature-sensitive material. In this way it is possible to instantly recognize an unauthorized use of an electronic device. It is also possible to check that a call has not been made from a mobile station for the purpose of eavesdropping leaving the line open in order to facilitate secret monitoring. In the same way it is of course possible to recognize a call left accidentally unfinished.
The devices most suitable for the use of the present invention are hand-held or portable electronic devices, like mobile stations, cordless phones, portable stereos, dictation machines, Personal Digital Assistants (PDA-devices), laptop computers, electronic games, watches, remote controllers, digital blood pressure gauges, virtual reality helmets, game controllers, computer mouses, pocket calculators and alarm clocks.
According to the invention, there is provided an electronic device with a cover, wherein the cover comprises thermochromic liquid crystals capable of at least partially reversible color change in order to bring about a change of color in response to a change in the temperature of the cover.
According to the invention, there is provided a cover to an electronic device, comprising thermochromic liquid crystals capable of at least partially reversibly color change in order to cause a color change in the cover in response to a temperature change in the cover.
According to the invention, there is provided a method for at least partially reversibly changing the color of an electronic device with a cover, comprising the steps of:
introducing in the cover thermochromic liquid crystals capable of color change; and
subjecting the cover to a change of temperature, whereby the color of the cover changes as a response to the change of temperature in the cover.